A typical over-head valve internal combustion engine includes a cylinder case defining at least one cylinder bore having a piston reciprocally movable therein. The piston and the cylinder bore cooperate with a cylinder head to form a variable volume combustion chamber. The cylinder head defines intake ports through which air, provided by an intake manifold, is selectively introduced to the combustion chamber. Additionally, the cylinder head defines exhaust ports through which exhaust gases or products of combustion are selectively evacuated from the combustion chamber. Typically, an exhaust manifold is affixed, by bolting or other fastening method, to the cylinder head such that the exhaust manifold communicates with each exhaust port to carry the exhaust gases from the internal combustion engine to a vehicular exhaust system for subsequent release to the atmosphere. Many aspects are considered when designing an exhaust manifold such as packaging constraints, weight, cost, flow performance, and durability. Durability may be a concern since the exhaust manifold and the head to which it is affixed are typically dissimilar metals with differing rates of thermal expansion. The differing rates of thermal expansion may cause stresses within both the cylinder head and the exhaust manifold.
Some modern internal combustion engines may employ a turbocharger. The turbocharger has a turbine portion and a compressor portion. The turbine portion has a turbine housing, which is in communication with the exhaust manifold. The turbine housing directs the heat, noise, and kinetic energy of the flowing exhaust stream to spin a turbine blade. The turbine blade is rigidly mounted to a compressor blade for unitary rotation therewith. As the compressor blade spins, the air is compressed within a compressor housing. The compressed air is subsequently introduced to the intake manifold to increase the volumetric efficiency of the internal combustion engine. To maximize the performance of the turbocharger, engine designers typically mount the turbine housing as close to the exhaust port as possible so that the heat energy that might otherwise be used to spin the turbine blade is not wasted through radiation to the atmosphere.